Envelopes of various types have been devised to provide for the security of the contents held within. The greatest disadvantage of these envelopes is that they can be opened and resealed without the knowledge of the recipient. The contents can therefore be accessed, partially removed or altered in such a way that the recipient will not be aware of such a tampering until a much later date, if at all. It is common knowledge that conventional paper envelopes can be easily opened with steam. The glue of the opened envelope may then be moistened and the envelope resealed, leaving no evidence of tampering. Even the more secure plastic envelopes can be opened with solvents which dissolve the seal. The contents of these higher security plastic envelopes can then be accessed and the envelopes resealed with the application of additional glue or cement, without alerting the recipient.
Bank night-depository envelopes are particularly vulnerable to security risks. Endorsed checks are inserted by the customer into an envelope which is handled by several persons until opened by a bank official who is unfamiliar with the original contents. Therefore, several checks may be removed without detection during the handling process, and discrepancies will not be evident until the depositor obtains the receipt.
Currently, the most common bank deposit security container consists of a cloth bag with a lockable zippered closure. One key to the bag is kept by the depositor and an additional key is maintained by the recipient such as a bank official. Unfortunately, such locks are not always secure, and if the lock is opened and the contents of the zippered bag removed or altered, the recipient will have no notice of the tampering until a discrepancy is discovered.
A bank depository bag was devised by Judd (U.S. Pat. No. 3,933,304) to protect against unauthorized invasions by printing information, such as the name of the bank, on the two heat-sealed edges of the bag. The heat-seal is located between the edge containing the printed information and the contents of the bag so that access to the bag can only be achieved by cutting the heat sealed edge, thus removing the printed information. If the bag is opened and resealed, the absence of the printed information is intended to alert the recipient to check for missing documents. One disadvantage to this device and other similarly sealing envelopes and packages is that heat-sealing equipment must be available to the person placing the contents in the bag. This creates an inconvenience and additional expense.
A high integrity tamper-resistant container secured by a permanent pressure sensitive seal was devised by Whelan (U.S. Pat. No. 4,483,018). Although this container is difficult to access and reseal without leaving evidence of an unauthorized entry, it is possible to compromise the security features of this container by cutting the envelope along one of the two heat-sealed edges, removing the contents and resealing the cut edge with heat. The detection of such an unauthorized access would be difficult for most recipients because the tamper-indicating border does not extend to the heat-sealed edges.
The personnel receiving any of the above-mentioned sealed envelopes must be educated on how to detect any unauthorized opening or must have an unopened envelope available for comparison.
Consequently, there is an immediate need for an inexpensive, tamper-evident envelope which indicates on its face that the seal has been broken.